Use default value obj for terminal check

exe/dead_end

@@ -70,7 +70,7 @@ warn "Record dir: #{options[:record_dir]}" if options[:record_dir]
 display = DeadEnd.call(
   source: file.read,
   filename: file.expand_path,
-  terminal: options[:terminal],
+  terminal: options.fetch(:terminal, DeadEnd::DEFAULT_VALUE),
   record_dir: options[:record_dir]
 )
 

lib/dead_end/display_invalid_blocks.rb

@@ -9,8 +9,9 @@ module DeadEnd
   class DisplayInvalidBlocks
     attr_reader :filename
 
-    def initialize(code_lines:, blocks:, io: $stderr, filename: nil, terminal: nil, invalid_obj: WhoDisSyntaxError::Null.new)
-      @terminal = terminal.nil? ? io.isatty : terminal
+    def initialize(code_lines:, blocks:, io: $stderr, filename: nil, terminal: DEFAULT_VALUE, invalid_obj: WhoDisSyntaxError::Null.new)
+      @terminal = terminal == DEFAULT_VALUE ? io.isatty : terminal
+
       @filename = filename
       @io = io
 

lib/dead_end/internals.rb

@@ -12,6 +12,10 @@
 require "timeout"
 
 module DeadEnd
+  # Used to indicate a default value that cannot
+  # be confused with another input
+  DEFAULT_VALUE = Object.new.freeze
+
   class Error < StandardError; end
   SEARCH_SOURCE_ON_ERROR_DEFAULT = true
   TIMEOUT_DEFAULT = ENV.fetch("DEAD_END_TIMEOUT", 1).to_i
@@ -27,14 +31,14 @@ def self.handle_error(e, search_source_on_error: SEARCH_SOURCE_ON_ERROR_DEFAULT)
     if search_source_on_error
       call(
         source: Pathname(filename).read,
-        filename: filename,
+        filename: filename
       )
     end
 
     raise e
   end
 
-  def self.call(source:, filename:, terminal: nil, record_dir: nil, timeout: TIMEOUT_DEFAULT, io: $stderr)
+  def self.call(source:, filename:, terminal: DEFAULT_VALUE, record_dir: nil, timeout: TIMEOUT_DEFAULT, io: $stderr)
     search = nil
     Timeout.timeout(timeout) do
       record_dir ||= ENV["DEBUG"] ? "tmp" : nil

spec/integration/exe_cli_spec.rb

@@ -50,17 +50,15 @@ def exe(cmd)
       end
     end
 
-    describe "terminal coloring" do
-      # When ruby sub shells it is not a interactive shell and dead_end will
-      # default to no coloring.
-
-      it "passing --terminal will force color codes" do
-        ruby_file = fixtures_dir.join("this_project_extra_def.rb.txt")
-        out = exe("#{ruby_file} --terminal")
+    # When ruby sub shells it is not a interactive shell and dead_end will
+    # default to no coloring. Colors/bold can be forced with `--terminal`
+    # flag
+    it "passing --terminal will force color codes" do
+      ruby_file = fixtures_dir.join("this_project_extra_def.rb.txt")
+      out = exe("#{ruby_file} --terminal")
 
-        expect(out.strip).to include("Missing `end` detected")
-        expect(out.strip).to include("\e[0m❯ 36  \e[1;3m    def filename")
-      end
+      expect(out.strip).to include("Missing `end` detected")
+      expect(out.strip).to include("\e[0m❯ 36  \e[1;3m    def filename")
     end
 
     it "records search" do

spec/unit/display_invalid_blocks_spec.rb

@@ -27,6 +27,50 @@ def hai
       expect(io.string).to include("Syntax OK")
     end
 
+    it "selectively prints to terminal if input is a tty by default" do
+      source = <<~EOM
+        class OH
+          def hello
+          def hai
+          end
+        end
+      EOM
+
+      code_lines = CleanDocument.new(source: source).call.lines
+
+      io = StringIO.new
+      def io.isatty
+        true
+      end
+
+      block = CodeBlock.new(lines: code_lines[1])
+      display = DisplayInvalidBlocks.new(
+        io: io,
+        blocks: block,
+        code_lines: code_lines
+      )
+      display.call
+      expect(io.string).to include([
+        "❯ 2  ",
+        DisplayCodeWithLineNumbers::TERMINAL_HIGHLIGHT,
+        "  def hello"
+      ].join)
+
+      io = StringIO.new
+      def io.isatty
+        false
+      end
+
+      block = CodeBlock.new(lines: code_lines[1])
+      display = DisplayInvalidBlocks.new(
+        io: io,
+        blocks: block,
+        code_lines: code_lines
+      )
+      display.call
+      expect(io.string).to include("❯ 2    def hello")
+    end
+
     it "outputs to io when using `call`" do
       source = <<~EOM
         class OH